Liquid telechelic polymers having high 1,4-diene structure

ABSTRACT

Liquid telechelic polymers are made from dienes and are produced via anionic polymerization. While having low molecular weight, for example less than 15,000, the telechelic polymers are generally gel-free, have high amounts of trans-1,4 structure, low vinyl unsaturation and low bulk viscosities. The liquid telechelic polymers are made utilizing a trimetallic initiator comprised of (1) an organopolylithium compound and (2) a complex of a trialiphatic substituted aluminum compound or derivative thereof and a barium salt of an organic alcohol.

This application is a continuation of application Ser. No. 200,286,filed on May 31, 1988, of I. Glen Hargis, Hubert J. Fabris, John A.Wilson, and Russell A. Livigni, for "Liquid Telechelic Polymers HavingHigh 1,4-Diene Structure."

FIELD OF THE INVENTION

The present invention relates to liquid telechelic polymers made fromconjugated dienes with the polymers being characterized by having hightrans and low vinyl unsaturation therein and low bulk viscosities. Thepolymers have such characteristics independent of chain length and aremade by utilizing a trimetallic initiator which is comprised of anorganopolylithium compound and a complex made from the barium salt of anorganic alcohol and a trialiphatic substituted aluminum compound.

BACKGROUND ART

Heretofore, telechelic polymers made from dienes had variousshortcomings or limitations arising from the polymerization process suchas high solution viscosity, high bulk viscosity, high vinyl contentwhich increased with lower molecular weight of the telechelic polymer,and the like. Often, gelation occurred. Such telechelic polymers weregenerally prepared utilizing only an organopolylithium initiator and apolar solvent to facilitate dissolution.

U.S. Pat. No. 3,278,508 to Kahle et al relates to the polymerization ofconjugated dienes such as 1,3-isoprene to form rubbery polymers having ahigh percentage of cis-1,4-addition product and reduced solutionviscosities utilizing an initiator of an organolithium in combinationwith an organoaluminum compound for producing high molecular weightpolymers.

U.S. Pat. No. 3,664,989 to Petrov et al relates to a method of preparinga homopolymer or a copolymer having terminal functional groups from aconjugated diene or optionally with a styrene type monomer having apre-set molecular weight wherein the polymerization is carried out inthe presence of an alkali metal catalyst such as lithium, and a modifierobtained by reacting an alkali metal with a conjugated hydrocarbon andan organoaluminum compound.

U.S. Pat. No. 4,518,753 to Richards et al relates to a process for theanionic polymerization of a conjugated diene in the presence of RLi anda hindered triaryl boron or aluminum derivatives.

British Patent No. 1,294,890 to Petrov et al relates to the productionof hydrocarbon polymers containing functional end groups by treating aconjugated diene polymer containing at the chain ends thereoforganometallic groups of a metal of Group II or Group III of thePeriodic Table but excluding a transitional metal, with a reagentselected from an alkylene oxide, carbon dioxide, oxygen, sulfur, andepichlorohydrin.

An article "Synthesis and Characterization of Functional Diene Oligomersin View of Their Practical Applications," Die Angewandte MakromolekulareChemie, 70 (1978)9-30 (Nr. 1032), relates to the utilization of variousinitiators for butadiene oligomerization.

An article "Functionally Terminal Polymers via Anionic Methods," Schulz,Sanda and Willoughby, Chapter 27, Anionic Polymerization, Kinetics,Mechanisms and Synthesis, Symposium Series No. 166, American ChemicalSociety, Washington, D.C., 1981, relates to reacting monoacetalpolybutadienyl lithium with ethylene oxide or carbon dioxide. Dihydroxyor hydroxy-carboxy terminated polymers are produced.

SUMMARY OF THE INVENTION

Low molecular weight liquid telechelic polymers made from dienes areproduced having a low vinyl content and a low bulk viscosity byutilizing a trimetallic initiator. The metallic initiator contains anorganopolylithium compound wherein the organic group is an aliphatic, anaromatic, or an alkyl substituted aromatic and desirably has two lithiumgroups therein. A preformed complex of a triorgano substituted aluminumand a barium salt of an organic alcohol is blended with theorganopolylithium compound. In order to produce a Wittig ate complex [G.Wittig, Angewandte Chem., 70, 65 (1958)] of barium and aluminum, themole ratio of the aluminum metal to the barium metal is approximately3.5 to about 4.5 whereas the mole ratio of the barium metal to thelithium metal is approximately from about 0.1 to about 0.5. Theinitiators are generally contained in various organic solvents so thatthey are dispersed therein. The dienes are generally conjugated dieneshaving from 4 to about 8 carbon atoms or optionally are copolymerswherein the comonomer is a different conjugated diene and/or a vinylsubstituted aromatic having from 8 to 12 carbon atoms such as styrene.Although low molecular weight polymers are produced, that is having anumber average molecular weight of 15,000 or less, the vinyl content ofthe polymer or copolymer is generally less than 15 percent but greaterthan 1 percent based upon the total amount of cis, trans, and vinylstructural groups therein derived from the diene monomers. The organicfunctional groups of the telechelic polymer are added afterpolymerization of the diene and the optional vinyl substituted aromaticmonomers and such functional groups can be acid groups, mercapto groups,amino groups, hydroxyl groups, halogen groups, and the like.

DETAILED DESCRIPTION OF THE INVENTION

The liquid telechelic polymers of the present invention are made fromdiene monomers and desirably conjugated dienes having from 4 to 12carbon atoms and preferably from 4 to 8 carbon atoms with specificexamples including isoprene, butadiene, 1,3-hexadiene, piperylene, andthe like, with butadiene being preferred. Such dienes are well known tothe art and to the literature and include various branched dienemonomers such as 2,3-dimethyl-1,3-butadiene, 3-methyl-1,3-heptadiene,and the like. Although homopolymers are preferred, random and blockcopolymers can also be utilized. The comonomer is either one or moredifferent conjugated dienes having from 4 to 8 carbon atoms and/or oneor more vinyl substituted aromatics having from 8 to 12 carbon atomssuch as styrene, alpha-methyl-styrene, p-tertiary butyl styrene, and thelike, with styrene being preferred. The amount of vinyl substitutedaromatic comonomer utilized is from about 0 to about 50 percent byweight and preferably from about 5 to about 25 percent by weight basedupon the total weight of all of the comonomers and the diene monomer.The molecular weight of the liquid telechelic diene polymers of thepresent invention is generally low and hence the homopolymer orcopolymer has a molecular weight of generally less than 15,000,desirably less than 5,000, and preferably less than 3,500, but has aminimum weight of at least 500. A molecular weight of from about 1,000to about 2,000 is often utilized.

The polymers of the present invention are formed by polymerizing theabove-noted diene monomers in the presence of an anionic initiatorsystem. The initiator system is generally a two component blendcontaining three metallic compounds with one of the blend componentsbeing an organopolylithium compound. Although the lithium component cancontain a plurality of lithium atoms therein such as three or four, twolithium atoms are preferred. The organo group is generally an aliphaticincluding cycloaliphatic, more desirably an alkyl, having from 2 to 12carbon atoms and preferably from 2 to 8 carbon atoms, an aromatic or analiphatic, desirably an alkyl, substituted aromatic having from 6 to 40carbon atoms with from 6 to 30 carbon atoms being preferred. Examples ofspecific organo portions or groups of the lithium initiator componentinclude divinyl benzene, diisopropenyl benzene, 1,1,4,4-tetraphenylbutane, 1,2-diphenylethene, 1,3-bis(phenylethenyl) benzene,1,2-dibutyl-1,2-diphenylethene, isoprene, and the like. Generally,lithium adducts of oligomers or dimers are preferred wherein the numberof repeating units in the oligomer is from 2 to about 10, with 2 toabout 6 being preferred. The lithium adducts are generally made fromdienes having from 4 to 12 carbon atoms, either straight-chained orbranched, as for example 1,3-butadiene, isoprene, dialkyl-butadieneswherein the alkyl group contains from 1 to 3 carbon atoms such as2,4-hexadiene, 2,5-dimethyl-2,4-hexadiene, 1,3,5-hexatriene allocimene,myrcene, and the like. An especially preferred difunctional lithiuminitiator is a dilithioisoprene oligomer having the following formula##STR1## where R =H or CH₃,

R'=CH₃ or H, with the proviso that R' is not the same as R

R"=1,4 and 3,4 isoprene adducts,

n =approximately 4.0

Average Molecular Weight =432 when n =4.0

The initiator is soluble in a mixture of cyclohexane and dimethyletherat a molar equivalent ratio of 1 mole of dimethylether per mole ofcarbon-lithium bond.

The second component of the anionic initiator system is a preformedcomplex of a trialiphatic substituted aluminum compound and a bariumsalt of an organic alcohol. Each aliphatic group of the aluminumcompound can independently contain from 1 to 20 carbon atoms, with from2 to 4 carbon atoms being preferred. Desirably the aliphatic is an alkylgroup. Examples of suitable aluminum compounds include trimethylaluminum, triethylaluminum, tri-n-propyl aluminum, triisopropylaluminum, pentyl diethyl aluminum, 2-methylpentyl-diethyl aluminum,tri-n-butyl aluminum, triisobutyl aluminum, dicyclohexylethyl aluminum,tri-n-pentyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum,tri(2-ethylhexyl)aluminum, tricyclopentyl aluminum, tricyclohexylaluminum, tri(2,2,4-trimethylpentyl)aluminum, tri-n-dodecyl aluminum andtri(2-methylpentyl) aluminum and the like, with triethylaluminum beinghighly preferred.

The barium compound is actually the salt of an organic alcohol whereinthe organic group is an aliphatic, desirably an alkyl, having from 1 to15 carbon atoms and preferably from 2 to 10 carbon atoms; an aromatic,or an alkyl substituted aromatic having from 6 to 20 carbon atoms, withfrom 6 to 10 carbon atoms being preferred. Mixed alcohols can also beutilized. Examples of suitable alcohols include methanol, ethanol,propanol, isopropanol, n-butanol, cyclopentanol, cycloheptanol,cyclohexanol, s-butanol, t-butanol, allyl alcohol, pentanol, hexanol,octanol, decanol, phenol, nonyl phenol, diallyl alcohol, ditertiarybutylalcohol, and the like, with diallyl alcohol being preferred.

The preformed aluminum/barium complex, that is the "ate" complex orcomponent is formed by adding the two compounds together, generallysuspended or dispersed in a solvent, and heating the same at atemperature of from about 75° C. to about 125° C. The mole ratio of thealuminum compound to the barium compound is generally from about 3.5 toabout 4.5, desirably from about 3.7 to about 4.3, and preferably fromabout 3.95 to about 4.05. The complexing temperature is generally fromabout 50° C. to about 125° C. with about 80° C. being optimum.

The trimetallic anionic initiator system of the present invention isformed by mixing the organopolylithium component with the preformedcomplex component of the aluminum compound and the barium compound. Theamounts of the two components are chosen such that the mole ratio ofbarium metal to lithium metal in the initiator is from about 0.10 toabout 0.50, desirably from about 0.20 to about 0.40, and preferably from0.22 to about 0.30. The obtained initiator system produces a low vinylstructure in the resulting diene polymer.

The lithium component and the preformed complex component of the anionicinitiator system are generally dispersed in various nonaromatichydrocarbon or nonpolar solvents. Suitable solvents include aliphaticsolvents such as alkane solvents having from about 5 to about 20 carbonatoms, desirably from 5 to about 10 carbon atoms, with 6 carbon atomsbeing preferred, such as pentane, hexane, heptane, decane, and the like;as well as cycloaliphatic solvents having from 5 to 10 carbon atoms.Hexane, heptane or cyclohexane are preferred. Other hydrocarbon solventsinclude paraffinic hydrocarbon solvents such as various petroleum ethersand the like. Naturally, mixtures of the above solvents can also beutilized. The amount of solvent is not critical so long as a suitableamount is utilized to generally disperse or suspend the particularcomponents of the anionic initiator system.

The amount of the anionic initiator system based upon the molar amountof the dilithium initiator compound is generally from about 0.2 to about2.0 moles, desirably from about 0.35 to about 1.5 moles, and preferablyfrom about 0.5 to about 1.0 mole for every 1,000 grams by weight ofdiene monomer and any optional vinyl substituted aromatic comonomer.

Polymerization of a diene monomer such as butadiene utilizing adilithioisoprenyl dimethyl ether complex in the absence of the bariumand aluminum complex results in a polybutadiene having from about 20 toabout 40 percent vinyl content at a number average molecular weight offrom 1,000 to 15,000. In contrast thereto, utilization of the anionictrimetallic initiator system of the present invention in the above-notedamounts produces low molecular weight polymers having unexpected andsignificantly low vinyl content therein. The amount of the vinyl contentis generally 15 percent or less, desirably 12 percent or less, andpreferably 10 percent or less based upon the total of all of the cis,trans, and vinyl structural groups in the polymers derived from dienemonomers. That is, this percentage is based only upon portions or unitsof the polymer or copolymer made from diene monomers, and not from unitsor portions made from vinyl substituted aromatic comonomers. The amountof the trans structural groups, that is the trans-1,4 groups, is atleast 65 percent and preferably at least 69 percent based upon the totalof all of the cis, trans and vinyl structural groups in the polymersderived from diene monomers. Another unexpected result is that the bulkviscosity of the polymer itself is significantly reduced over heretoforemade polymers derived from diene monomers. The bulk viscosity of thepolymers (i.e., solvent free) of the present invention is generally 60poise or less, desirably 45 poise or less, and preferably 30 poise orless at a molecular weight of about 1,000 and at a temperature ofapproximately 21° C. The solution viscosity is also low and thusimproved processability is obtained.

The liquid telechelic polymers of the present invention generally cancontain up to two organic functional groups. Various functional orendcapping groups can be chemically bonded to the terminal lithiumportions of the polymer such as hydroxy groups, carboxylic acid groups,mercapto groups, amino groups, halogen groups, and the like. Thefunctional or endcapping groups are added to the polymer by reacting acompound containing such groups with the polymer in the presence of aninert atmosphere. The addition of such functional or endcapping groupsto lithium terminated polymers are well known to the art and to theliterature. For example, polymers having hydroxyl endcapping groups canbe prepared by reacting the lithium terminated polymer with variousepoxides, aldehydes, or ketones. Acid end groups can be added bytreating the polymer with carbon dioxide or with various cyclicanhydrides. Mercapto end groups are produced when sulfur, cyclicsulfides, or disulfides are utilized. Chlorine end groups can beprepared by reaction with chlorine. Amino end groups are added byreacting with mixtures of methoxyamine and methyl lithium, as well aswith tertiary amino substituted aromatic aldehydes and ketones. Polymerscontaining hydroxyl or carboxylic acid functional end groups arepreferred. The hydrocarbon portions of the various types of the abovereaction compounds are known to the art and to the literature as forexample as set forth in the references listed in Advances inOrganometallic Chemistry, Stone & West, Volume 18, 1980, Academic Press,New York, New York, pages 89 through 93, by A. F. Halasa et al which ishereby fully incorporated by reference. Another article which sets forthvarious terminal telechelic end groups as well as the preparationthereof is set forth in the article "Telechelic Polymers-Precursors toHigh Solids Coatings," Progress In Organic Coatings, 7 (1979) 289-329,and is hereby fully incorporated by reference. Such endcapping compoundsare reacted with the polymer obtained from diene monomers attemperatures of from about ambient for example 25° C. to about 100° C.and more desirably from about 25° C. to about 70° C. Such reaction, asnoted, is carried out in an inert atmosphere such as argon or nitrogenwith the proviso that oxygen or oxygen-containing compounds such aswater, carbon dioxide, and air should be excluded since they would reactwith the initiator. The amount of functional or endcapping compoundsutilized is generally a large excess to ensure that essentially all orsubstantially all of the lithium terminated polymers are reacted andcontain a functional or endcapping group thereon. Typically, the moleratio of the functional or endcapping compound to carbon-lithium of thelithium terminated polymers is at least 1.5, desirably greater than 2,and often from about 3 to about 4. Naturally, very large excesses, forexample 20 or 30, can be utilized as when a carbon dioxide gas isutilized to add carboxylic acid end groups.

The liquid telechelic polymers of the present invention made from dieneshave several advantages which clearly distinguish them from prior artpolymers. A low process viscosity provides improved rheological behaviorincluding efficient mixing with fillers such as aluminum and salts ofperchloric acid, carbon black, calcium carbonate, magnesium silicate,silica, and the like. The generally high 1,4-structure and theassociated low glass transition temperature (less than minus 65° C.) ofthe polymers of the present invention impart excellent low temperatureelastomeric properties. Hence, the polymers of the present inventionhave application in situations requiring low vitrification temperatures.Since high amounts of trans-1,4- content or structure (about 70 percent)is contained within the polymers, they can provide low levels ofcrystallinity and provide networks with improved fatigue life andcut-growth resistance. Accordingly, the polymers of the presentinvention can be utilized as binders as for solid fuel rocketpropellants, coatings, intermediates for polyurethanes, and the like.

The invention will be better understood by reference to the followingdescription of the polymer characterization and examples.

Polymer Characterization

Composition and percent polybutadiene microstructure were obtained from¹³ C NMR. Number average molecular weights were determined with aHitachi vapor pressure osmometer. Hydroxyl content was determined byacetylation with acetic-1-¹⁴ C anhydride, followed by isolation andradioassay of the product. Gel permeation chromatograms were obtainedusing a Waters High Performance Gel Permeation Chromatograph, Model150C. Solutions at 0.5 weight percent in THF were injected onto columnsat a flow rate of 1 ml/minute. The instrument oven and the differentialrefractometer were at 30° C. The column set (styragel) configurationused, as designated by Waters Associates, was 10⁵ Å+10⁴ Å+10³ Å+10² Å.

All thermal transitions were obtained by differential scanningcalorimetry (DSC) using a heating rate of 20° C./minute. Glasstransition temperatures (Tg) were determined from the midpoint of theinflection in the plot of heat flow with temperature in the heatingcurve at a heating rate of 20° C./minute, obtained after quenching thesample from 125° C. to minus 150° C.

Bulk viscosity (poise) of the liquid polymers were determined with aBrookfield viscometer (20 rpm spindle rotation) at room temperature.

Gel content was determined in toluene using a Harris cage.

Williams Plasticity

The hydroxyl terminated polybutadienes were crosslinked with DesmodurL-2291A, 1,6-hexamethylene diisocyanate adduct of trimethylolpropane offunctionality 3.0 from Mobay Chemical Company. Dibutyltin dilaurate wasused as a catalyst. The materials were crosslinked in an oven at 80° C.for four hours. A Williams Plastometer was used to determine theplasticity, expressed in mils and taken after three minutes.

Functionality

This entity was calculated from the ratio of number average molecularweight, determined with vapor pressure osmometry, and equivalent averagemolecular weight, determined by radiochemical assay of acetylated endgroups containing carbon-14.

EXAMPLE 1

A hydroxy terminated polybutadiene (HTPB) was prepared with a Ba/Al/DiLiinitiator system as shown in Table I. The trimetallic catalyst wasprepared by the addition of a solution of dilithium (DiLi) oligomer(0.415 mM/g) of isoprene in cyclohexane (containing 3 weight percentdimethyl ether) to a solution of preformed Ba/Al complex in cyclohexane.This complex was obtained by adding a solution of triethylaluminum (2.17mM/g) in cyclohexane to a suspension of barium diallyl oxide (0.213mM/g) in cyclohexane and heating at 80° C. for 1 hour to provide a clearsolution. A polybutadiene (Run 1, Table I) was prepared with thisBa/Al/DiLi catalyst in cyclohexane in a one liter glass bottle reactor.For comparison purposes, a control polybutadiene (Run 2, Table I) wasobtained using only DiLi as the initiator. All polymerizations werequantitative and their solution viscosities in cyclohexane were nearlyequivalent. However, the addition of ethylene oxide (4 moles per molecarbon-lithium) to the DiLi initiated polybutadiene (Run 2) produced anextremely viscous gel-like mass that did not flow at room temperature.The solution viscosity of the high-1,4 polybutadienyl anions of Run 1was only slightly increased. It should be noted that upon addition ofisopropanol (15 g), the solution viscosities of the hydroxylpolybutadienes of Runs 1 and 2 were reduced to the same level. Theliquid polymers were recovered by treating the reaction mixture withcitric acid (34 g) dissolved in a mixture of 4 liters water and 0.1liter isopropanol. The resulting mixtures were allowed to stand for onehour and then the cyclohexane phase containing the liquid polymers wereseparated, antioxidant (1 phr A.0. 2246) added, and the products wererecovered in a rotary evaporator. The predicted number-average molecularweight based on the ratio of incorporated butadiene, isoprene(initiator) and ethylene oxide to moles of carbon-lithium was 1020,compared to measured M_(n) values of 975 and 1130 for Runs 1 and 2,respectively.

                                      TABLE I                                     __________________________________________________________________________    Preparation of Hydroxyl Terminated Polybutadiene with Ba/Al/DiLi              Run                                                                              Polym..sup.a                                                                         Butadiene                                                                           Initiator.sup.b                                                                         Mole Ratios                                                                           Ethylene                                                                              %   %                               No.                                                                              Temp. (°C.)                                                                   (grams)                                                                             Ba Al DiLi.sup.c                                                                        Al/Ba                                                                             Ba/Li                                                                             Oxide (grams)                                                                         Conv..sup.d                                                                       Vinyl                           __________________________________________________________________________    1  65     100   0.090                                                                            0.369                                                                            0.374                                                                             4.1 0.24                                                                              66      100 11                              2  65     100   -- -- 0.374                                                                             --  --  66      100 40                              __________________________________________________________________________     .sup.a polymerized in cyclohexane (380 g)                                     .sup.b moles per 100 g butadiene                                              .sup.c moles of carbonlithiumin solution of DiLi per 100 g butadiene          .sup.d based on 100 g butadiene, 74 g isoprene contributed by the             initiator, and 16.8 g ethylene oxide incorporated as --CH.sub.2 CH.sub.2      OH per carbon lithium                                                    

As apparent from Table I, Run 1 utilizing a trimetallic initiator of thepresent invention produced a hydroxyl terminated polybutadienecontaining a significantly low amount, that is less than 11 percent byweight of vinyl groups based upon the total number of cis, trans, andvinyl groups within the polymer. In contrast thereto, Run 2 whichutilized only a conventional organodilithium initiator of the prior artproduced a polymer containing 40 percent by weight of vinyl groupstherein.

EXAMPLE 2

A comparison of vinyl content, hydroxyl end group functionality and Tgof HTPB's of various molecular weights is shown in Table II. Thepolymers were prepared with the Ba/Al/DiLi catalyst system described inExample 1 and with the DiLi catalyst, as indicated in Table II. Apolybutadiene (R-45HT) produced by Arco Chemical Co. and reported as atelechelic hydroxy terminated polybutadiene obtained by a free radicalinitiation [M. Kanakavel Makromol. Chem., 188,845 (1987)] is provided(in Run 7) for comparison purposes. The data clearly show that the useof the Ba/Al complex in combination with DiLi substantially reducesvinyl content and lowers Tg below the value obtainable with DiLi with nosacrifice in hydroxyl functionality. The extent of reduction in vinylcontent is independent of molecular weight. The vinyl content of theHTPB's of this disclosure remains at about 10 percent for the limitedrange of molecular weights (975 and 1650) shown. For HTPB's preparedwith DiLi, vinyl content increases from 28 to 40 percent with a decreasein molecular weight from 4500 to 1860. The data in Table II show that,for HTPB's with M_(n) ≦2000, the level of vinyl unsaturation can bedecreased from about 40 to 10 percent by the use of Ba/Al/DiLi catalyst.With the drop in vinyl content, a concomitant change in Tg from minus50° C. to minus 65° C. can be seen.

                                      TABLE II                                    __________________________________________________________________________    Run     Mole Ratio                                                                              % Diene Structure                                                                            Hydroxyl                                     No.                                                                              Initiator.sup.a                                                                    Al.sup.3+ /Ba.sup.2+                                                                 Mn Vinyl                                                                             Trans                                                                             Cis                                                                              Tg, °C.                                                                    Functionality                                __________________________________________________________________________    1  I    4.0     975                                                                             11  69  20 -66 1.5                                          2  II   (DiLi alone)                                                                         1130                                                                             40  38  22 -50 1.5                                          3  I    4.2    1650                                                                              9  70  21 -65 1.6                                          4  II   (DiLi alone)                                                                         1860                                                                             40  37  23 -51 1.4                                          5  II   (DiLi alone)                                                                         2420                                                                             36  35  25 -56 1.7                                          6  II   (DiLi alone)                                                                         4540                                                                             28  42  30 --  1.6                                          7.sup.b                                                                          III    --   2800                                                                             20  60  20 --  2.3                                          __________________________________________________________________________     .sup.a I  barium diallyl oxide/triethylaluminum with dilithium adduct of      isoprene complexed with dimethyl ether                                        II  dilithium adduct of isoprene complexed with dimethyl ether                III  free radical                                                             .sup.b HTPB (R45HT) produced by Arco Chemical Company                    

For anionic polymerization of diene monomers initiated by organolithiumcompounds in hydrocarbon solvents, a Poisson molecular weightdistribution (MWD) is characteristic of polymers of high degrees ofpolymerization. The MWD distribution is often broadened for lowmolecular oligomers prepared with high concentrations of certaindilithio initiators; however, the degree of polydispersity isconsiderably less than for a corresponding radical initiated HTPB(R-45HT). A comparison of the data in Table III of HTPB's prepared withBa/Al/DiLi and DiLi shows that the MWD's are nearly the same. Bothanionic polymers have narrower MWD's than R45HT, as indicated by theirM_(w) /M_(n) values.

                  TABLE III                                                       ______________________________________                                        Run                   By HPGPC                                                No.     Initiator.sup.a                                                                          -- M.sub.n                                                                           -- M.sub.n                                                                           -- M.sub.w                                                                          -- M.sub.w /-- M.sub.n                 ______________________________________                                        1       I           975   1400   2000  1.43                                   2       II         1130   1400   2200  1.57                                   7       III        2800   4670   13400 2.87                                   ______________________________________                                         .sup.a See Table II for description of initiators                        

EXAMPLE 3

An HTPB was prepared according to Example 1 (Run 1) in the absence ofthe barium component utilizing an Al/DiLi (mole ratio =1/1) complex asthe initiator system. The data in Table IV show that Al/DiLi can reducethe vinyl content from 40 to 25 percent as well as reduce the amount oftrans-1,4 content to a level such that the polymer is amorphous, but itis considerably less effective than the Ba/Al/DiLi catalyst system forobtaining vinyl contents as low as 10 percent and a trans content ashigh as 70 percent at nearly the same molecular weight.

In addition to a low vinyl structure, the data in Table IV show a muchhigher trans/cis ratio of HTPB (Run 9) compared to HTPB's (Runs 4 and8). The higher level of trans-1,4 placements in combination with asufficient chain length may provide a crystallizable trans-HTPBtelechelic with implications of improved elastomeric properties.

                                      TABLE IV                                    __________________________________________________________________________    Run       Mole Ratio % Diene Structure                                                                            Hydroxyl                                  No.                                                                              Initiator.sup.a                                                                      Al/Li                                                                             Ba/Li                                                                             -- M.sub.n                                                                       Vinyl                                                                             Trans                                                                             Cis                                                                              Tg, °C.                                                                    Functionality                             __________________________________________________________________________    4  DiLi   --  --  1860                                                                             40  37  23 -51 1.4                                       8  Al/DiLi                                                                              0.86                                                                              --  1440                                                                             25  45  30 -57 1.5                                       9  Ba/Al/DiLi                                                                           0.96                                                                              0.24                                                                              1490                                                                              9  71  20 -65 1.5                                       __________________________________________________________________________

EXAMPLE 4

As discussed in Example 1, when solutions of dilithium polybutadiene(Run 2) are reacted with ethylene oxide, the viscosity of the solutionrises markedly and a stiff gel forms as a result of association of thepolymeric electrolyte. In contrast to this behavior, solutions ofpolybutadiene (prepared with Ba/Al/DiLi) terminated with ethyleneoxideexhibit only a small increase in solution viscosity, such that thesolution remains fluid.. Thus, mixing problems associated with gelationcan be avoided without resorting to the use of polar solvents to breakup the association of ions.

As previously mentioned, low polymer viscosity is another characteristicof the telechelic high 1,4-polybutadienes. The data in Table V showthat, at nearly the same number-average molecular weight andpolydispersity values, there is a threefold decrease in polymerviscosity on going from 40 to 11 percent vinyl content. The lowerviscosity of the low molecular weight HTPB's of this invention, largelyaccounted for by the reduced vinyl content, can provide obviouspractical advantages in applications such as castable elastomers.

                  TABLE V                                                         ______________________________________                                        Run                         %     Tg,  Viscosity,                             No.  Initiator.sup.a                                                                        -- M.sub.n.sup.b                                                                     -- M.sub.w /-- M.sub.n.sup.c                                                         Vinyl °C.                                                                         poise at 21° C.                 ______________________________________                                        1    I         975   1.48   11    -66  27                                     2    II       1130   1.53   40    -50  84                                     ______________________________________                                         .sup.a see Table II for description of initiators                             .sup.b measured by vapor pressure osmometry                                   .sup.c measured by high performance gel permeation chromotography        

EXAMPLE 5

The HTPB's of Example 1 were cured with an adduct of 1,6-hexamethylenediisocyanate and trimethylolpropane and catalyzed with dibutyltindilaurate. A comparison of the Williams plasticity values (Table VI) atequivalent mole ratios (NCO/OH) demonstrates that the quality of thehydroxyl terminated polybutadienes of this invention are equivalent tothe control material made with a dilithio compound as the soleinitiator.

                  TABLE VI                                                        ______________________________________                                                           RUN NO.                                                                       1    2                                                     ______________________________________                                        Initiator            I      II                                                Hydroxyl Functionality                                                                             1.5    1.5                                               Williams Plasticity.sup.a (mils)                                                                   340    310                                               % Gel.sup.b           85     83                                               ______________________________________                                         .sup.a Values reported for polyurethanes prepared with a mole ratio           (NCO/OH) of 1.1.                                                              .sup.b In toluene.                                                       

While in accordance with the Patent Statutes, the best mode andpreferred embodiment has been set forth, the scope of the invention isnot limited thereto, but rather by the scope of the attached claims.

What is claimed is:
 1. A liquid telechelic polymer comprising:an organofunctional terminated telechelic polymer, the organo functional groupbeing hydroxyl, carboxyl, mercapto, amino, halogen, or combinationsthereof, the telechelic polymer being the polymerization product of (a)a conjugated diene monomer having from 4 to 12 carbon atoms, (b) anoptional different diene monomer having from 4 to 12 carbon atoms, and(c) an optional vinyl substituted aromatic monomer having from 8 to 12carbon atoms, said telechelic polymer having a functionality of at least1.4, a number average molecular weight of less than 15,000 and a vinylstructural unit content of less than 15 percent and a trans-1,4 contentof at least 65 percent based upon the total number of vinyl, trans, andcis structural units in said telechelic polymer derived from theconjugated diene monomers.
 2. A liquid telechelic polymer according toclaim 1, wherein the amount of said optional vinyl substituted aromaticmonomer is from about 0 to about 50 percent by weight based upon thetotal weight of all of the diene monomers and said optional vinylsubstituted aromatic monomer.
 3. A liquid telechelic polymer accordingto claim 2, wherein the molecular weight of said telechelic polymer isfrom about 500 to about 15,000, wherein the functionality of saidtelechelic polymer is at least 1.7, and wherein said vinyl structuralunit content is 12 percent or less.
 4. A liquid telechelic polymeraccording to claim 3, wherein the conjugated diene monomers have from 4to 8 carbon atoms, wherein said telechelic polymer is a homopolymer, andwherein the molecular weight of said homopolymer is from about 500 toabout 5,000.
 5. A liquid telechelic polymer according to claim 4,wherein the molecular weight of said homopolymer is from about 1,000 toabout 2,000, wherein said conjugated diene monomer is butadiene, andwherein said liquid telechelic polymer is a viscosity of 60 poise orless at 21° C.
 6. A liquid telechelic polymer according to claim 5,wherein said organo functional group is hydroxyl, or carboxylic acid,wherein said vinyl structural unit content is 10 percent or less, andwherein said trans-1,4 content is at least 69 percent.
 7. The liquidtelechelic polymer of claim 1, made utilizing a trimetallic initiator,said trimetallic initiator comprising a blend of an organopolylithiumcomponent and a preformed complex component made from a trialiphaticsubstituted aluminum compound and a barium salt of an organic alcohol.8. The liquid telechelic polymer of claim 2, made utilizing atrimetallic initiator, said trimetallic initiator comprising a blend ofan organopolylithium component and a preformed complex component madeform a trialiphatic substituted aluminum compound and a barium salt ofan organic alcohol, wherein the mole ratio of the aluminum metal to thebarium metal is from about 3.5 to about 4.5, wherein the mole ratio ofsaid barium metal to the lithium metal is from about 0.10 to about 0.50,and wherein the amount of said trimetallic initiator is from about 0.2to about 2.0 moles per 1000 grams of the monomers.
 9. The liquidtelechelic polymer of claim 4, made utilizing a trimetallic initiator,said trimetallic initiator comprising a blend of an organopolylithiumcomponent and a preformed complex component made from a trialiphaticsubstituted aluminum compound and a barium salt of an organic alcohol,wherein the organo portion of said organopolylithium component is analiphatic having from 2 to 12 carbon atoms, an aromatic or an aliphaticsubstituted aromatic having from 6 to 40 carbon atoms, or an oligomerhaving from 2 to 10 repeat units made from a diene having from 4 to 12carbon atoms, wherein the aliphatic portion of said trialiphaticsubstituted aluminum compound independently is an aliphatic having from1 to 20 carbon atoms, wherein said organic alcohol is an aliphaticalcohol having from 1 to 15 carbon atoms, an aromatic or an alkylsubstituted aromatic having from 6 to 20 carbon atoms, wherein the moleratio of the aluminum metal to the barium metal is from about 3.7 toabout 4.3, and wherein the mole ratio of said barium metal to thelithium metal is from about 0.20 to about 0.40.
 10. The liquidtelechelic polymer of claim 6, made utilizing a trimetallic initiator,said trimetallic initiator comprising blend of an organopolylithiumcomponent and a preformed complex component made from a trialiphaticsubstituted aluminum compound and a barium salt of an organic alcohol,wherein the organo portion of said organopolylithium component is anoligomer having from 2 to 10 repeat units made from a diene having from4 to 12 carbon atoms, wherein the polylithium portion is dilithium,wherein the aliphatic portion of said trialiphatic substituted aluminumcompound independently is an alkyl having from 2 to 4 carbon atoms,wherein said organic alcohol forming said barium salt is an aliphaticalcohol having from 2 to 10 carbon atoms, wherein the mole ratio of thealuminum metal to the barium metal is from about 3.95 to about 4.05, andwherein the mole ratio of said barium metal to the lithium metal is fromabout 0.22 to about 0.30.